Occurrence of Mercaptopyruvate Sulfotransferase Activity in Photosynthetic Organisms

Abstract

Mercaptopyruvate sulfotransferase activity catalyzes the formation of pyruvate from mercaptopyruvate in the presence of suitable reagents as acceptor. It was detected in Lemna minor, Pisum sativum, Spinacia oleracea, Chlorella fusca, Synechococcus 6301, and Rhodopseudomonas palustris. Best activity was detected using dithioerythritol as a thiol reagent; good activity was obtained using mercaptoethanol, glutathione, mercaptopyruvate or sulfite as acceptor. The pH-optimum for the Chlorella mercaptopyruvate sulfotransferase was found around 9; the apparent Km for mercaptopyruvate was determined to 2 mM and for dithioerythritol for 5 mM using crude Chlorella extracts. The role of this enzyme is discussed in relation to cysteine catabolism by photosynthetic organisms. © 1984, Walter de Gruyter. All rights reserved.